“Obviously this is going to be a grueling process all the way through,” Rodriguez said. “This has been a burden. It’s been a big burden. So let’s get it on.”

A three-time AL MVP, Rodriguez is fifth on the career home run list with 654. The Major League Baseball Players Association says the penalty imposed by baseball Commissioner Bud Selig is excessive. Unless there is a settlement, a decision isn’t expected until the winter.

A veteran of baseball salary arbitration, the 64-year-old Horowitz took over as the sport’s grievance arbitrator in June 2012 from Shyam Das, fired a month earlier by management after almost 13 years. Das had overturned a 50-game suspension of Milwaukee outfielder Ryan Braun in February after the players’ association argued the urine sample was not handled properly.

In Horowitz’s only decision thus far, he upheld a 100-game suspension imposed last year on San Francisco reliever Guillermo Mota for a second positive test. He has initially set aside Monday through Friday for the hearing, where each side can introduce evidence, present witnesses and cross-examine them.

After the hearing days conclude, the sides will be given several weeks to submit final briefs. Horowitz will then take time to make his decision. While technically chairman of a three-person panel, Horowitz is the independent member joined by one representative of each side.

Rodriguez has four law firms working for him, with team A-Rod including Joseph Tacopina of Tacopina Seigel & Turano (known for taking cases with a high media-profile); David Cornwell of Atlanta-based Gordon & Rees (who worked on Braun’s case); Jordan Siev, co-head of the U.S. commercial litigation group at Reed Smith (a firm used by Rodriguez pal Jay-Z); and Bruce Simon of Cohen, Weiss & Simon (who represented MLB umpires in 1999).

Earlier this year, Rodriguez retained and then terminated two other firms.

Yet, for all the outside legal help, much of the case will be presented by 55-year-old David Prouty, a Harvard Law School graduate hired by the players’ association in 2008 from UNITE HERE, which represents employees in the hotel, gaming and food service industries. Prouty was promoted to MLBPA general counsel in February, when union head Michael Weiner gave up that role a half-year after he made public he had been diagnosed with a brain tumor.

Rob Manfred and Dan Halem, MLB’s top labor lawyers, will direct management’s case with assistance from Proskauer Rose, a law firm that represents several U.S. leagues.

“It’s been one of the most challenging years of my career, without a doubt,” A-Rod said.

MLB said Rodriguez’s was suspended under baseball’s joint drug agreement “based on his use and possession of numerous forms of prohibited performance-enhancing substances, including testosterone and human growth hormone over the course of multiple years.” He also was disciplined under the collective bargaining agreement “for attempting to cover up his violations of the program by engaging in a course of conduct intended to obstruct and frustrate the office of the commissioner’s investigation.”

Rodriguez is being treated as a first offender under the drug program, which means any suspension doesn’t start unless upheld by an arbitrator.

Following hip surgery in January and a leg injury sustained during a minor league rehabilitation assignment in June, Rodriguez returned to the Yankees on the day he was suspended. The 38-year-old hit .244 with seven homers and 19 RBIs in 44 games.

“I’m really looking forward to at least one full offseason of hardcore training,” he said. “I haven’t had that in quite a long time – then come back in tremendous shape and help this team win. This team has a lot of things to do over the winter. Obviously my situation is going to play a big part in it.”

“You’ll hear the full story when the time is right for me,” Rodriguez said. “That time is not just now.”

He is owed $86 million by the Yankees over the last four seasons of his record $275 million, 10-year contract. If he is suspended for the bulk of next season, the team has a chance to get under the luxury tax threshold of $189 million.

But the length of any suspension will be decided by either Horowitz or in an agreement among Rodriguez, MLB and the union.

“I will be there every day,” Rodriguez said. “I’m fighting for my life and my whole legacy.”